A 10.0mL sample of HNO3 was diluted to a volume of 100.0mL. 25mL of the dilute solution was needed to neutralise 50.0mL of a 0.60M KOH solution. What was the concentration of the original nitric acid?

1 Answer

Best answer

The 25mL HNO3 solution is double the concentration of KOH, i.e. 1.2M because you needed half the volume of 50mL to neutralise it. (Note this only works because KOH and HNO3 are in a 1:1 ratio, so you should check the balanced reaction first!)

Then you can work backwards from there. If the 25mL dilute solution comes from a 10x dilution (10mL -> 100mL), then the original nitric acid was 10x stronger, i.e. 12M is the answer